Conventionally, in the production of semiconductor devices, fine processing by lithography using a photoresist has been performed. The fine processing is a processing method for forming fine convexo-concave shapes corresponding to the following pattern on the surface of a substrate by: forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer; irradiating the resultant thin film with active rays such as ultraviolet rays through a mask pattern in which a pattern of a semiconductor device is depicted; developing the thin film; and subjecting the substrate to etching processing using the resultant photoresist pattern as a protecting film.
Recently, high integration of semiconductor devices has progressed and the adopted active rays tend to have a shorter wavelength, such as an ArF excimer laser (193 nm) and EUV light (13.5 nm), replacing a KrF excimer laser (248 nm). Following such a tendency, the influence of reflection of active rays on a semiconductor substrate has become a large issue.
Thus, in the production of semiconductor devices in recent years, for achieving various effects such as the reflection preventing effect, a resist underlayer film has become disposed between the semiconductor substrate and the photoresist.
For example, as an underlayer film between the semiconductor substrate and the photoresist, the use of a film known as a hardmask containing a metal element such as silicon (see, for example Patent Document 1) has been performed. In this case, the resist and the hardmask have components largely different from each other, so that the removal rates of the resist and the hardmask by dry etching largely depend on the type of a gas used for dry etching. By appropriately selecting the type of a gas, the hardmask can be removed by dry etching without a large decrease in the film thickness of the photoresist. Thus, the studies of a composition for a resist underlayer film have been performed; however, due to the diversity of characteristics required for the composition and so on, development of a novel material for the resist underlayer film is desired.
There is also a method for modifying the surface of the substrate from another viewpoint. For example, there is disclosed a method for changing the surface of the substrate after exposure to hydrophilic using a silane coupling agent having a sulfonyl group (see Patent Document 2).
A resist underlayer film containing silicon having a sulfonamide group is also disclosed (see Patent Documents 3 and 4).